Project Summary/Abstract There is a lack of structural interventions to improve antiretroviral therapy (ART) adherence, which represents missed opportunities to reduce HIV health disparities. Economic disadvantage can contribute to poor medication adherence and clinical outcomes through mediators such as limited social resources, repeated cycles of housing instability, high levels of stress caused by financial insecurity, and lack of resources to cope with these demands. Treatment as Prevention is an important method of improving clinical outcomes for people living with HIV/AIDS (PLWHA) and reducing secondary transmissions; however, for this approach to be optimized, rates of ART adherence must be improved and sustained. Client-Centered Representative Payee is a structural intervention that provides financial management support to PLWHA by modifying the implementation of a long-standing policy within the Social Security Administration, in which an organization is authorized to serve as the client's payee. The central hypothesis of this study is that by helping clients to pay rent and other bills on time, housing stability will improve and financial stress will decrease. By reducing the cognitive burden of living with chronic financial stress and frequent threats of housing loss, clients can devote more time and attention to medical appointments and medication adherence. It is further hypothesized that these changes will improve clients' self-efficacy for health behaviors, retention in care, medication adherence, and viral loads. These hypotheses will be tested via the following specific aims: (1) Conduct a randomized controlled trial (n=320) to test the effect of Client-Centered Rep Payee on ART adherence and viral load among PLWHA who are economically disadvantaged and unstably housed. Clinical adherence will be compared through behavioral and biological measures including prescription refill data, self-reported appointment adherence, and viral load for patients receiving the intervention versus those receiving standard of care. (2) Test underlying mechanisms associated with Client-Centered Rep Payee that contribute to changes in medication adherence and viral suppression rates. This will be accomplished via use of quantitative (mediation analysis) and qualitative (semi-structured interview) methods to test hypothesized mediators of medication adherence and viral suppression including financial and housing instability, financial stress, self- efficacy for health behaviors, and retention in care. (3) Assess the cost and cost-effectiveness of the Client- Centered Rep Payee model. An economic analysis will be conducted to model the impact of the intervention as compared with standard of care on quality adjusted life years as well as new infections averted. This approach is innovative because it offers a structural intervention to improve adherence by addressing the effects of economic insecurity, requires low financial investment, and can be layered with existing clinical services. Further, it is highly scalable as it builds on a current policy in practice within the Social Security system.